Isaac Klein is a regular at Punderdome, performing under the nom de pun, “Punder Enlightening.” Photo: Astrid Stawiarz

The lowly pun has long been considered the bottom-feeding bristle worm of the comedy world, shunned by improv teachers citywide and annoying, well, pretty much everyone.

That has changed with the arrival of Punderdome 3000, a now monthly event that has turned punning into a high-functioning competition that is equal parts stand-up, beat poetry and, as one audience member described it, “freestyle rap for white people.”

What began two years ago as a small affair in a club basement has grown into a competition that regularly sells out the 350-capacity

Littlefield club in Gowanus, Brooklyn, and draws locally famous judges ranging from comedians Michael Showalter and Jon Glaser to critics from The New Yorker and the New York Times.

The competition, which will have its 21st iteration on Tuesday, is the brain child of Brooklyn comedian Jo Firestone, 26, who co-hosts — appropriately, seeing as puns are the ultimate dad jokes — with her Rodney Dangerfield-impersonating father Fred, 60.

While Punderdome is inspired by the O. Henry Pun-Off that’s been held for 35 years in Austin (slogan: “Jest for a wordy cause!”), the NYC event has a more casual format. Eighteen contestants sign up and pick their nom de pun, including Do Pun to Others, Edible Punties, Well He Quipped and Black Punther.

Five or six contestants at a time compete in heats. The hosts drop a category (say “birds,” “Saturday morning cartoons” or “feminist theory”) and contestants get 90 seconds to think of puns, which can be as simple as rapid-fire word association or as elaborate as a sonnet.

On the category of household chores, one contestant blurted out, “Who’s ready to Roomba?” Another quipped, “Cleaning windows is such a pane!”

Weaving your puns into a story helps, as does going for the non-obvious joke.

When prompted with the category “presidents,” one contestant described robbing a Manhattan bank with some ex-presidents. When he got in the getaway car, he shouted, “FDR, Drive!”

The audience votes for its favorite measured by a “Human Clap-O-Meter,” a person blindfolded in a chair who moves the meter according to how loud the crowd gets. In the final two rounds, the celebrity judges weigh in, “American Idol”-style, before the audience has its say. First and second place each get to take home one of two Mystery Boxes that contain some absurd prize, often direct from the As-Seen-On-TV aisle: past prizes have included a piñata, a milkshake machine and a penguin onesie (a k a a “pun-sie”).

Tim Taylor, 25, a software developer from Sunnyside, Queens, doubled over with guffaws in his first-row seat at February’s event, his first time attending. When he first heard of Punderdome, he didn’t picture this.

“We had no idea what the hell to expect,” he says. “It’s hard to explain.” He and his friends were even a bit envious of the skill of the punmasters.

Part of the success of the event is in making it an interactive, crowd-friendly experience, according to Fred Firestone. “We want people to walk away saying ‘I didn’t just attend, I was a part of it,’ ” says Firestone, who flies in from his home in St. Louis every month to host.

“It’s a spectator sport.”

When he’s not punning, Firestone does corporate seminars and business speaking. When his daughter called him asking for advice on how to host the first event, he remembered he had a game-show set in his garage from a previous client, and offered to bring it out.

The success of the show has changed their father-daughter dynamic, especially with relation to his lame jokes.

“I’m not used to this kind of thing; I’m used to an eye roll,” he says.

“As a father, the opportunity to collaborate with my daughter on an activity that is vindicated by others, it’s rock ’n’ roll, it’s exciting.”

The show is looking to expand beyond Brooklyn: the Firestones filmed a pilot that was shown at the New York Television Festival last year, and they’re looking to bring Punderdome to colleges and other events. And they’re offering free tickets for a year to anyone who can land the ultimate celebrity judge: Stephen Colbert.

The event has already won over Jason Zinoman, the New York Times comedy critic and February’s celebrity judge, who was originally hostile to puns. “With these incredibly inventive puns, I don’t look down at puns at all,” he says. “From Henny Youngman to James Joyce, these people have used puns to great effect. I don’t want to say it’s a high art, but it’s an art.”

You wanna say something punny?

I once took a trip to the Colorado River and the guide told me there were two ways to traverse it. I could get on a raft and use paddles, or I could swim. Basically, it was a choice: “Row vs. wade.” (feminism puns) — Brian Agler, a k a Punda Express

I saw some orphaned ducks on the side of the road and just thought, “Where are these foundlings’ fathers?” (Constitution puns) — Rekha Shankar, a k a Punky Brewster

“I bought my fern health insurance so I could have fronds with benefits.” — (plant puns) — Conal Darcy, a k a Well He Quipped